Glutaminyl-tRNA synthase (glutamine-hydrolysing)

Template:Cs1 config Template:Infobox enzyme Glu-tRNA^Gln amidotransferase or glutaminyl-tRNA synthase (glutamine-hydrolysing) enzyme (Template:EnzExplorer) is an amidotransferase that catalyzes the conversion of the non-cognate amino acid glutamyl-tRNA^Gln to the cognate glutaminyl-tRNA^Gln.. It catalyzes the reaction:

ATP + glutamyl-tRNA^Gln + L-glutamine $\rightleftharpoons$ ADP + phosphate + glutaminyl-tRNA^Gln + L-glutamate

This enzyme belongs to the family of ligases, specifically those forming carbon-nitrogen bonds carbon-nitrogen ligases with glutamine as amido-N-donor. The systematic name of this enzyme class is glutamyl-tRNA^Gln:L-glutamine amido-ligase (ADP-forming). This enzyme participates in glutamate metabolism and alanine and aspartate metabolism.

Function and evolutionary significance

Most bacterial and all archaea genomes do not encode a glutaminyl-tRNA synthetase (GlnRS). Instead they first synthesize the attachment of an amino acid on the tRNA^Gln by first attaching a non-cognate glutamate to the tRNA. Then these organisms use the amidotransferase: glutaminyl-tRNA synthase (glutamine-hydrolysing) (Template:EnzExplorer) enzyme to convert the glutamate attached to tRNA^Gln to glutamine.